How to handle the Guest Complain.?

Hai sir.., My view on your question menrtioned below.

Follow tha rule of "LAST"

L= Listen the guest with out intrepting his words or with out argument

A = Apologise for the complaint

s = Suggest a remedy to solve the complaint

T = Thanks to the guest 

First Listen carefully completly regognize Guest complain then politly give him/her to reply & say sory by heart oplogize say never happen again then solve the problem.